Deferred Costs, Acquired Lease Intangibles and Goodwill - Narrative (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018	Jun. 30, 2020	Dec. 31, 2013
Deferred Costs [Line Items]
Amortization of deferred leasing and acquired deferred leasing costs	$ 24,800	$ 24,500
Amortization of deferred leasing and acquired deferred leasing costs			$ 26,300
Amortization of acquired above and below-market leases, net	3,627	7,311	6,120
Goodwill	491,479	491,479
Observatory Reporting Unit
Deferred Costs [Line Items]
Fair value in excess of carrying value (less than) (as a percent)				5.00%
Empire State Building observatory operations
Deferred Costs [Line Items]
Goodwill					$ 227,500
Empire State Building
Deferred Costs [Line Items]
Goodwill					250,800
501 Seventh Avenue
Deferred Costs [Line Items]
Goodwill					$ 13,200
Lease agreements
Deferred Costs [Line Items]
Amortization expense related to acquired lease intangibles	$ 7,600	10,900	$ 12,100
Ground lease
Deferred Costs [Line Items]
Weighted-average amortization period (in years)	23 years 7 months 6 days
In-place leases and deferred leasing costs
Deferred Costs [Line Items]
Weighted-average amortization period (in years)	3 years 10 months 24 days
Above-market leases
Deferred Costs [Line Items]
Weighted-average amortization period (in years)	3 years 7 months 6 days
Below-market Lease
Deferred Costs [Line Items]
Weighted-average amortization period (in years)	3 years 8 months 12 days
Unsecured revolving credit facility | Revolving Credit Facility
Deferred Costs [Line Items]
Net deferred financing costs	$ 2,100	$ 4,200